POS0221 CLINICAL, LABORATORY AND ULTRASONOGRAPHIC FINDINGS AT BASELINE CAN PREDICT THE LONG-TERM OUTCOME OF POLYMYALGIA RHEUMATICA
Authors: E. Conticini, P. Falsetti, M. D’alessandro, C. Baldi, S. Grazzini, S. G. Al Khayyat, R. D’alessandro, S. Gentileschi, F. Bellisai, C. Barreca, C. Acciai, E. Bargagli, L. Cantarini, B. Frediani
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> No definite clinical, laboratory or imaging finding has been identified to predict prognosis and different clinical course of PMR, nor the risk of further relapses. <h3>Objectives</h3> Primary endpoint was to assess the rate of PMR patients who, during the follow-up, undergo a diagnosis of GCA and arthritis, as well as to assess which clinical, laboratory and US findings are associated to a diagnostic shift and predict the long-term evolution of PMR. Secondary endpoint was to assess the optimal use of US in PMR. <h3>Methods</h3> All patients who were diagnosed with PMR in our Rheumatology Unit from January 2017 to January 2022 and followed-up for at least 12 months were retrospectively included. If performed at the time of diagnosis, musculoskeletal and temporal (TA) and axillary arteries (AxA) US findings were recorded, too. <h3>Results</h3> A total of 201 patients (mean age 73.4 ± 7.63, M/F 89/112) were included. According to the US performed at baseline, patients were subdivided in 4 subgroups: in 32 of them, the diagnosis was only clinical (A); 35 underwent shoulders, hips, wrists and knees US (B); 48 underwent shoulders, hips, TA and AxA US (C), while 86 shoulders, hips, wrists, knees, TA and AxA US (D). At baseline, 14/132 (10.6%) of patients from groups C and D displayed findings consistent with GCA. During the follow-up, 47%, 52.8% and 60% of PMR patients who were re-evaluated at 12, 24 and 36 months, respectively, had a change in diagnosis (<b>figure 1</b>). The multivariate logistic regression showed that bilateral LHBT tenosynovitis at onset was the variable that better defined the persistence in PMR diagnosis (p=0.05, OR 8.425), whereas GH synovitis (p=0.022, OR 0.074) and RF positivity (p=0.028, OR 0.993) were the variables associated to a diagnostic shift on the follow-up. The model that better described (AUROC 0.854) a patient with a PMR-onset with subsequent diagnostic shift comprised higher frequency of bilateral GH synovitis, bilateral shoulder PD, higher values of CRP, WBC, PLT and Hb and longer time to obtain remission. On the other hand, the ones maintaining diagnosis of PMR had bilateral exudative LHBT tenosynovitis (OR 8.425) and SA-SD bursitis (OR 2.619), higher values of ESR (OR 1.015), lower values of Hb (OR 0.428) and shorter time to remission (OR 1.076). Continuous variables were included in a hierarchical clustering analysis identifying two groups. Cluster 2 identified older patients, with lower systemic inflammation, lower levels of WBC, PLT and Hb, who had a higher persistence in PMR diagnosis at 12 (42.7% vs 29.3%), 24 (37.2% vs 25.6%) and 36 months (36.4% vs 21.2%). Cluster 2 had lower frequency of PD positivity (PD 0 in 39.1% on shoulders and 47.1% on wrists) or peripheral synovitis (absence of synovitis on knee and MCF in 43.9% and 50% respectively), more frequent flares, and were taking PDN at 12 (until 45.8%) and 24 months (until 30.8%). An environmental trigger before onset were more commonly reported (in 5,8% vaccinations before onset, vs 1.4% in cluster 1) The comparisons among the B, C and D and A showed significant differences in diagnosis at 12 (p=0.0145) and 24 months (p=0.0432) and dosage of GC at 12 months (p=0.0009). At 12 months the complete withdrawal of PDN was achieved in a significant (p=0.002) lower number of patients belonging to group A (6.4%) when compared to group B (28.1%), C (37,5%) and D (12.9%). A direct correlation was obtained between GC dosage at 12 and 24 months (Spearman rho 0.284, p=0.002). Finally, a longer time to remission correlated positively with CRP and negatively with Hb, while fever at disease onset positively with ESR. <h3>Conclusion</h3> More than half patients fulfilling criteria for PMR have their diagnosis changed during follow-up. The early use of US is associated with a more accurate diagnosis at baseline, as well as to a lower cumulative dosage of PDN. The early diagnosis of GCA is possible only in case of AxA and TA US at diagnosis. On the other hand, the lack of US is associated to a prolonged PDN treatment. Patient with a definite subset of clinical (fever, short time to remission), laboratory (lower Hb and CRP, higher ESR) and US findings (lower PD signal, LHBT tenosynovitis) are more prone to maintain the diagnosis of PMR during the follow-up. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.